Kinetic, Mechanistic, and Thermodynamic Profiling of Alkaline Hydrolysis of Ethyl Acetate in Mixed Aqueous Solvents

International Journal of Chemistry | Vol. 2, No. 8, August 2011 | pp. 84–91

DOI: 10.46882/2011/IJC/000035

Article Type: Original Research Paper

Title: Kinetic, Mechanistic, and Thermodynamic Profiling of Alkaline Hydrolysis of Ethyl Acetate in Mixed Aqueous Solvents

Names of Authors: T. M. Usman¹, H. U. Dikko¹*

Authors’ Affiliations:
¹Department of Chemistry, Bayero University, Kano, Nigeria.

Abstract: Investigating reaction velocities in mixed binary solvents yields important insights into solute-solvent interactions, transition state solvation, and dielectric impacts on reaction kinetics. The alkaline hydrolysis of ethyl acetate by sodium hydroxide was investigated titrimetrically in water-ethanol and water-acetone binary solvent mixtures across varying compositions (10% to 50% v/v) and temperatures (298.15 K to 318.15 K). The reaction followed second-order kinetic behavior, displaying a first-order dependence on both the ester and the hydroxyl ion concentrations. The specific rate constant (k) decreased systematically with increasing concentrations of the organic co-solvent in the reaction medium. This trend is attributed to the reduction of the dielectric constant of the medium, which destabilizes the polar activated complex relative to the isolated reactants. Activation parameters were computed via the Arrhenius and Eyring expressions. In 30% ethanol, the activation energy (Ea) was 48.5 kJ/mol, the enthalpy of activation (delta H*) was 45.8 kJ/mol, and the entropy of activation (delta S*) was -94.2 J/mol K. The highly negative entropy values confirm that the transition state possesses a more structured orientation than the ground-state reactants.

Keywords: Reaction kinetics; Alkaline hydrolysis; Ethyl acetate; Dielectric constant; Activation parameters; Solvation effects

Manuscript Timeline: Received: March 12, 2011; Revised: April 25, 2011; Accepted: May 14, 2011; Published: August 06, 2011.

Citation: Usman, T. M., & Dikko, H. U. (2011). Kinetic, Mechanistic, and Thermodynamic Profiling of Alkaline Hydrolysis of Ethyl Acetate in Mixed Aqueous Solvents. International Journal of Chemistry, 2(8), 84–91.

Subscribe to read the full article: https://www.internationalscholarsjournals.org/subscribe-to-read